Effects of Dietary Supplementation with Fermented Ginkgo Leaves on Innate Immunity, Antioxidant Capability, Lipid Metabolism, and Disease Resistance Against Aeromonas hydrophila Infection in Blunt Snout Bream (Megalobrama amblycephala)

Abstract

This study was conducted to investigate the effect of Candida utilis and Aspergillus niger, combined with fermented Ginkgo biloba leaves (FGB) on immunity, antioxidant capability, lipid metabolism, and disease resistance against Aeromonas hydrophila infection in juvenile blunt snout bream (Megalobrama amblycephala). Fish were fed basal diets supplemented with fermented Ginkgo biloba leaves FGB1(0.125%), FGB2(0.25%), FGB3(0.5%), FGB4(1.0%), or Control (0.00%) respectively. At the end of the 60-day feeding trial, fish were challenged by A. hydrophila and mortality rate was recorded for the next 7 days. Results showed that, compared with the control, serum myeloperoxidase (MPO) activity of groups FGB1 and FGB2, alkaline phosphatase (AKP) and lysozyme (LZM) activity of group FGB2 increased significantly (P<0.05), while malondialdehyde (MDA) and low density lipoprotein cholesterol (LDL-C) contents of group FGB2, immunoglobulin M (IgM) activity of group FGB4 decreased significantly (P<0.05). Furthermore, Acid phosphatase (ACP), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH) and triglyceride (TG) activities were not affected (P>0.05). After A. hydrophila challenge, the relative mortality of group FGB1 and FGB2 were significantly lower than the control (P<0.05), however the highest rate was in group FGB4. Results of this study indicate that dietary supplementation of 0.125%~0.25% fermented G. biloba leaves can significantly enhance immunity, antioxidant capability, and lipid metabolism of blunt snout bream, as well as improve its disease resistance.